Heunis was elected to parliament in 1970, and in 1974
became Minister of Indian Affairs and Tourism in the government of John
Vorster. In 1975, he became
Minister of Economic Affairs.

In 1979, as part of the PW
Botha Government, he participated in the preparation of a new constitution, and in
1982, became Minister of
Constitutional Reform. In this role, he put in place the tricameral
parliament, gave the right to vote to
Indians, and the coloured,
in separate chambers of the South African parliament. He convinced
the leader of the Coloured Labour Party, Allan
Hendrickse, to agree to this reform.

During this time, he took part in confidential informal
interviews in Port
Elizabeth between two NP representatives, and two
representatives from the ANC.

In September 1986, Heunis was
unanimously voted leader of the NP Federation of Cape Province,
taking over from President P.W. Botha. He was seen as a figure to
take over from the "old crocodile" and run the country.

However, his ascension was halted when he was not elected to the
leadership, beaten by 39 votes in Helderberg by the former NP MP
and South African ambassador to London, Dennis Worrall.

At the beginning of 1989, he
assumed the functions of President for the interim for 100 days
when Pieter Botha suffered a cerebral congestion.

He was one of the candidates for leadership of the National
Party, along with Pik
Botha, Barend du Plessis and Frederik de
Klerk, but was beaten in the second round of elections.

Later, Heunis retired from political life, and did not
participate in the elections of 1989, and returned to his law practice in Somerset West with
his son Jakkie Heunis.

He received an honorary doctorate in philosophy from the University
of Stellenbosch, honorary lieutenant-colonel of the police,
honorary citizen of George, decorated with the Grand Cordon of the
order of the Republic of
China, and was father of four boys and one girl. Chris Heunis
died in January 2006 in Somerset
West after a long illness.